Update mysql Docker tag to v8.1

Author: renovate[bot]

docker-compose.yml

@@ -31,7 +31,7 @@ services:
 
   # MySQL Database Container
   database:
-    image: 'mysql:8.0'
+    image: 'mysql:8.1'
     environment:
       - MYSQL_ROOT_PASSWORD=root
       - MYSQL_DATABASE=helmet